There is known a method of estimating the position of a vehicle by matching map information and information detected by sensors such as a camera and a range finder. The accuracy of the own-position estimation can be improved by using map information with three-dimensional information, but this method has problems of an increase in the cost of creating the map information and an increase in the processing load of the own position estimation. Meanwhile, there is proposed a technique in which a mobile body estimates the position of itself by using map information having information on landmarks described as two-dimensional information (see Japanese Patent Application Publication No. 2008-250906). Such a technique can reduce the cost of creating the map information and the processing load of the own-position estimation.
However, the technique described in Japanese Patent Application Publication No. 2008-250906 is based on the premise that the information obtained by the sensors and matched with the map information for the own-position estimation is information obtained within a predetermined distance from the latest own position. In this case, when a linear route continues for a predetermined distance or more and the information on the landmark is described as a straight line parallel to the route, there is a certain degree of freedom in the direction along the straight line and this may cause a decrease in accuracy of the own-position estimation.